1. Field of the Invention
This invention relates to a projector device, and more particularly, to an improvement of project device for projecting color images.
2. Description of the Related Art
Heretofore, there is such projector device that displays a red component, a green component, and a blue component of the image data on three CRTs (cathode-ray tube) separately. On the front of this projection type three-tube projector device, three CRTs are disposed. On the side where image projection surfaces of CRTs reside, a red filter, a green filter, and a blue filter are disposed sequentially and respectively along with their projection lenses.
On projecting, CRTs separately project a red component, a green component, and a blue component of the image data, directly on the screen. A projected light of a red component, a projected light of a green component, and a projected light of a blue component which are emitted by respective CRTs are synthesized to form a single image, so that a color image is displayed as a whole.
Other than the projection type three-tube projector device, there exists a reflection type three-tube projector device which comprises three CRTs in its box. In the case of this type of projector device, an optical path similar to that of a projection type three-tube projector device is reflected and turned by a mirror which is placed inside the box, and the projected light is thrown on a semitransparent screen in the form of a frosted glass, from the back side of the screen.
Hereby projected lights of red, green, and blue components thrown by respective CRTs are synthesized on the screen to form a single image, so that a color image is displayed as a whole. In the case of the reflection type three-tube projector device, the optical path is reflected to miniaturize the device and a screen itself is unified, so that a projector device smaller than a projection type three-tube projector device can be attained, and usage by users can be facilitated.
However, as to a projection type three-tube projector device and a reflection type three-tube projector device both having the above mentioned constitution, owing to the fact that CRTs are utilized as the light source and that the images emitted by those CRTs are enlarged on the display screen, there are problems that the whole device unavoidably becomes to a large size, and it is difficult to increase the brightness of the displayed images.
To solve these problems a projector device has been proposed, in which three liquid-crystal panel boards are used as an image source in place of CRTs, and a red component, a green component, and a blue component are separately displayed on each of the liquid-crystal panel boards, while lights are applied to one side of the liquid-crystal panel boards, and the resulted transmitted lights are separately passed through a red filter, a green filter, and a blue filter, and then focused into an image on the screen.
In case of the liquid-crystal projector device, by using the liquid-crystal panel boards, the whole size of the device can be substantially miniaturized than that of a device using CRTs. However, since a liquid-crystal panel board itself has a poor light transmission factor, this device is practically insufficient in terms of the brightness of the displayed images.
Meanwhile, a display system which uses a mirror deflection type light modulator (hereinafter referred to as a "mirror light bulb"), in which microscopic mirror elements are arranged so as to form a plane, according to the arrangement of the pixels, has been proposed (Japanese Patent Application Laid Open No. 179781/1985, No. 40693/1991 and No. 174112/1991).
It is considered that if a projector device for projecting enlarged color images can be formed utilizing this mirror light bulb as an image source, the constitution of the whole device can be simplified and miniaturized to a scale similar to a liquid-crystal projector device, and the brightness of the displayed images can be remarkably increased because the utilization ratio of the light source of the device can be improved as compared with a liquid-crystal.